Glenoid implant surgery using patient specific instrumentation

ABSTRACT

A pin placement instrument for placing a pin in a bone comprises an anatomical interface with a hook-like portion being opened in a lateral direction of the instrument to receive a bone therein in a planned position. A drill guide is connected to the anatomical interface and defining at least one guide slot in a longitudinal direction of the instrument. The guide slot has a lateral opening over its full length in the drill guide to allow lateral withdrawal of the instrument in said lateral direction with the pin placed in the bone passing through the lateral opening. A bushing is removably placed in said guide slot via said longitudinal direction in a planned fit, the bushing defining a throughbore aligned with the guide slot and adapted to receive the pin extending in said longitudinal direction when the bushing is in the guide slot for pin placement.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 14/386,620 filed on Sep. 19, 2014, which is a national stageentry of PCT/CA2013/050253 filed on Mar. 28, 2013, which claims priorityfrom provisional application Nos. 61/675,955 filed on Jul. 26, 2012,61/659,272 filed on Jun. 13, 2012 and 61/616,623 filed on Mar. 28, 2012,incorporated herewith by reference.

FIELD OF THE APPLICATION

The present application relates to shoulder replacement, morespecifically to glenoid implant shoulder surgery for instance in totalshoulder replacement, and to patient specific instrumentation (PSI) usedtherefore.

BACKGROUND OF THE ART

The use of implants in shoulder surgery is well-known. In such shouldersurgery, implant components are installed on the glenoid portion of thescapula (i.e., shoulder blade) and/or on the humerus, to replicate theshoulder joint. When an implant is installed on the scapula, it iscommonly installed in the glenoid cavity, also known as the glenoid orglenoid fossa. The glenoid is a cavity that receives the head of thehumerus in an anatomical shoulder. When an implant is used with theglenoid, the base of the implant is located within the glenoid, andcould be secured thereto by fasteners such as screws, or using cementand/or fixation peg or keel.

One of the challenges when installing an implant in the glenoid relatesto the positioning of implant. Due to the presence of ligaments and likesoft tissue, the positioning of the implant must be planned to replicateas much as possible the normal bio-mechanical movements of the humerusrelative to the scapula. Another challenge relates to the positioning ofthe fasteners that secure the implant to the scapula. Indeed, thescapula is relatively thin, and is surrounded by soft tissue. In orderfor the implant to be solidly secured to the scapula, the screws must bedeep enough within the bone material. However, unless desired by thesurgeon, the screws must not pierce through the bone surface so as notto damage soft tissue, such as nerves ligaments, tendons, etc.

Patient specific instrumentation (hereinafter “PSI”) pertains to thecreation of instruments that are made specifically for the patient. PSIare typically manufactured from data using imagery to model bonegeometry. Therefore, PSI have surfaces that may contact the bone in apredictable way as such contact surfaces are specifically manufacturedto match the surface of a bone. It would therefore be desirable to usePSI technology in shoulder surgery.

SUMMARY OF THE APPLICATION

It is therefore an aim of the present disclosure to provide a method forperforming glenoid implant surgery using patient specificinstrumentation.

It is a further aim of the present disclosure to provide patientspecific instrumentation for glenoid implant surgery.

Therefore, in accordance with one aspect of the present invention, thereis provided a pin placement instrument for placing a pin in a bonecomprising: an anatomical interface with a hook-like portion beingopened in a lateral direction of the instrument to receive a bonetherein in a planned position; a drill guide connected to the anatomicalinterface and defining at least one guide slot in a longitudinaldirection of the instrument, the at least one guide slot having alateral opening over its full length in the drill guide to allow lateralwithdrawal of the instrument in said lateral direction with the pinplaced in the bone passing through the lateral opening; and at least onebushing removably placed in said guide slot via said longitudinaldirection in a planned fit, the bushing defining a throughbore alignedwith the guide slot and adapted to receive the pin extending in saidlongitudinal direction when the bushing is in the guide slot for pinplacement.

Further in accordance with aspect of the present disclosure, wherein thedrill guide comprises two of said guide slot.

Still further in accordance with aspect of the present disclosure, thetwo said guide slots are parallel to one another.

Still further in accordance with aspect of the present disclosure, theat least one bushing has an abutment end for limiting movement in thelongitudinal direction when placed in the guide slot.

Still further in accordance with aspect of the present disclosure, asocket in the drill guide is adapted to receive a handle for distalmanipulation.

Still further in accordance with aspect of the present disclosure, atleast one said pin is provided for each set of the guide slot and thebushing, the bushing being in sliding engagement on the pin.

Still further in accordance with aspect of the present disclosure,surfaces of the hook-like portion are generally transverse to thelongitudinal direction.

Still further in accordance with aspect of the present disclosure, thehook-like portion has at least one patient specific surface based on ananatomical model of the patient.

Still further in accordance with aspect of the present disclosure, theanatomical model of the patient is that of a scapula, the at least onepatient-specific surface being complementary to a shape of at least oneof the scapula head and glenoid neck.

Still further in accordance with aspect of the present disclosure, theat least one guide slot is longitudinally aligned with at least one of aplanned center of an implant, a location adjacent to the superiorglenoid rim in alignment with the coracoid, and a base of the coracoid.

Therefore, in accordance with another aspect of the present disclosure,there is also provided a method for resurfacing a glenoid, comprising:obtaining a patient specific instrument with at least two pin slots;installing a pin slot of the patient specific instrument over a firstpin secured to the scapula; installing a cannulated reamer over a secondpin secured to the glenoid; installing a shaft slot of the patientspecific instrument over a shaft of the cannulated reamer to form ajoint between the shaft slot and the shaft of the cannulated reamerallowing a translational movement of the cannulated reamer along thesecond pin; and reaming the glenoid using the cannulated reamer asguided by the patient specific instrument and the pins.

Further in accordance with this other aspect of the present disclosure,obtaining the patient specific instrument comprises obtaining thepatient specific instrument with an end of the shaft slot distal fromthe glenoid at a patient specific distance from the glenoid, and furthercomprising stopping a reaming once a stopper on the shaft of thecannulated reamer abuts the end of the shaft slot.

Still further in accordance with aspect of the present disclosure, themethod comprises obtaining the cannulated reamer with the stopper on theshaft at a patient specific distance as a function of a planned depth ofreaming.

Still further in accordance with aspect of the present disclosure,installing the shaft slot of the patient specific instrument over theshaft of the cannulated reamer comprises rotating the patient specificinstrument about the first pin for the shaft of the cannulated reamer tobe received in the shaft slot via a lateral opening in the shaft slot.

In accordance with yet another aspect of the present disclosure, thereis provided a method for positioning an implant in a resurfaced glenoidcavity, comprising: obtaining a patient specific instrument with atleast one pin slot; installing the pin slot of the patient specificinstrument over a pin secured to the scapula; installing a shaft of animpactor in a guide bracket of the patient specific instrument such thatthe shaft is aligned with the resurfaced glenoid cavity, a translationaljoint being formed between the shaft and the guide bracket allowing atranslational movement of the shaft along the guide bracket; installingthe implant at the free end of the impactor; and forcing the implantinto the resurfaced glenoid cavity as guided by the patient specificinstrument and the pin.

Still further in accordance with aspect of the present disclosure,obtaining a patient specific instrument comprises obtaining a patientspecific orientation of the guide bracket such that an orientation ofthroughbores in the implant relative to the resurfaced glenoid cavity isas a function of planned positioning of screws received in thethroughbores of the implant.

Still further in accordance with aspect of the present disclosure, themethod further comprises positioning a drill guide in the implant forcedinto the resurfaced glenoid cavity, the drill guide comprising a visualpointer positioned to point toward the pin.

Still further in accordance with aspect of the present disclosure,forcing the implant into the resurfaced glenoid cavity as guided by thepatient specific instrument and the pin comprises moving the implant ina single translation degree of freedom.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of a method for securing a glenoid implant on ascapula, using patient specific instrumentation;

FIG. 2 is a perspective view of a scapula with a glenoid implant, invirtual planning;

FIG. 3 is a pair of perspective views of a pin placement PSI inaccordance with an embodiment of the present disclosure;

FIG. 4 is a perspective view of the scapula with the pin placement PSIof FIG. 3, during placement of pins;

FIG. 5 is a perspective view of the scapula of FIG. 4, during theremoval of the pin placement PSI;

FIG. 6 is a perspective view of a depth drilling PSI in accordance withanother embodiment of the present disclosure;

FIG. 7 is a perspective view of the scapula with the depth drilling PSIof FIG. 6;

FIG. 8 is a perspective view of the scapula and depth drilling PSI, witha cannulated reamer;

FIG. 9 is a perspective view of the scapula with the reamed glenoid;

FIG. 10 is a perspective view of an impactor guide PSI in accordancewith yet another embodiment of the present disclosure;

FIG. 11 is a perspective view of the scapula with the impactor guide PSIand impactor tool;

FIG. 12 is a perspective view of a drilling guide PSI in accordance withyet another embodiment of the present disclosure;

FIG. 13 is a perspective view of the scapula with the drilling guide PSIand drill bit;

FIG. 14 is an assembly view of a glenoid hemispherical implant;

FIG. 15 is a perspective view of a scapula with a glenoid implant and agraft; and

FIG. 16 is a lateral view of a pin placement PSI of FIG. 4, on thescapula.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring to the drawings and more particularly to FIG. 1, there isillustrated at 10 a method for securing a glenoid implant on a scapula(i.e., scapula) In order to perform the method, patient specificinstrumentation of various kinds are used, and will be referred tohereinafter as PSI, with reference to FIGS. 2-13. By way of example,FIG. 2 features the positioning of a glenoid hemispherical head implantbase on the scapula, in reverse total shoulder surgery. However, themethod 10 may alternatively be used to secure a cup implant in theglenoid as performed on anatomic total shoulder replacement.

According to step 11 of FIG. 1, virtual shoulder surgery planning isperformed. In this planning step, various shoulder structures aredisplayed as three-dimensional models, along with a model implant andits components. These 3-D models are typically the result of theprocessing pre-operative imagery (e.g., CT scans, MRI, etc) and henceare a precise and accurate representation of a patient's bones.

During the planning step, the operator may select various types anddimensions of implants and interactively plan where the implant and itscomponents will be located on the scapula and humerus. In the case ofthe glenoid implant, the position and orientation thereof may include avirtual representation of the position and orientation of the screwsthat will secure the glenoid implant to the scapula. Due to the lengthof the screws and the thinness of the scapula medial to the glenoid, thevirtual planning of the location of the glenoid implant typically aimsat finding an orientation and depth for the screws that will not havethem pierce through the bone material.

For example, there is illustrated at FIG. 2 a model of the scapula A ofthe patient with parts of an implant 20 (also shown in FIG. 14), theimplant 20 being of the ball head type (i.e., a hemispherical head 20A).The implant 20 comprises a base plate 21. The base plate 21 is of thetype made of a metal that will be adhered and fitted in a resurfacedglenoid cavity C (FIG. 9). For instance, a trabecular-like medical grademetal may be used for the base plate 21. A peg 22 projects from anunderside of the base plate 21 and will be accommodated in a boredrilled in the glenoid cavity B. Screws 23 also project from theunderside of the base plate 21 and anchor the implant 20 to the scapulaA. A body 25 is secured to the base plate 21, as these parts aregenerally monolithic The body 25 is the interface of the implant 20 witha hemispherical ball head that will define the surface contacting thehumerus or implant thereon. Throughbores 26 are hence concurrentlydefined in the body 25 and base plate 21, with the screws 23 passingthrough these throughbores 26.

Steps 12 to 17 of the method 10 are used to guide the surgeon oroperator in performing bone alterations so as to replicate the virtualshoulder surgery planning of step 11. Hence, steps 12 to 17 the method10 are performed to ensure that the glenoid implant is installedsubstantially similarly to the virtual planning.

According to step 12, PSI are generated using the data obtained from thevirtual planning. The PSI will be described in further detailhereinafter. Any appropriate manufacturing method and materials may beused for the PSI, provided that the PSI are precise and accuraterepresentations of the PSI required as a result of the virtual planning.The generation of PSI according to step 12 is performed preoperativelyusing the imagery data that is also used for the step 11 of virtualshoulder surgery planning. Any other source of anatomical data may alsobe used, such as manual bone measurements, obtained pre-operatively.Another information that may be obtained via the planning step is thegeneration of a required graft. It may be required to use a graft wedgeB1 between the implant and the scapula, and the planning step maytherefore define a model of required graft, as shown in FIG. 15, as wellas a PSI tool to shape the graft wedge B1 to a predetermined geometrycalculated in the virtual planning. The graft wedge B1 would bepositioned between the implant 20 and the machined glenoid cavity C. Theuse of a graft may be required for scapulas limited to a shallow glenoidcavity C, i.e., that does not have a full counterbore shape. Hence, asshown in FIG. 15, the graft wedge B1 would form concurrently with thecavity C the surface against which the implant 20 is applied.

Steps 13 to 17 are performed intra-operatively. The steps are performedonce the shoulder joint has been exposed and the humerus has beendislocated, resected and/or separated from the scapula A (FIG. 2).

According to step 13 (FIG. 1), a pair of pins are placed in the scapulaA using PSI. Referring concurrently to FIGS. 3 and 4, a pin placementPSI is generally shown at 30. The pin placement PSI 30 comprises ananatomical interface 31. The anatomical interface 31 has a laterallyopened hook-like shape so as to receive therein both sides of thescapula head and/or neck of the glenoid B. In accordance with PSI, theanatomical interface 31 has a contact surface(s) 32 that is manufacturedto match the corresponding surface on the patient's scapula.Accordingly, the positioning of the pin placement PSI 30 will be guidedby the contact surface 32 finding its corresponding matching surface onthe scapula A.

The pin placement PSI 30 further comprises a drill guide 33. The drillguide 33 is positioned relative to the anatomical interface 31 as afunction of the virtual planning of step 11 (FIG. 1). The drill guide 33has a pair of cylindrical cutouts or slots 34 that are specificallypositioned and oriented to guide the drilling of the pins in the glenoidB, i.e., the slots 34 extend in the longitudinal direction of the PSI30. According to an embodiment, lateral openings 35 allow lateral accessto the slots 34 such that the pins may be laterally inserted into theslots 34. A socket 36 or like connector may also defined in the drillguide 33 to facilitate the manipulation of the pin placement PSI 30. Forinstance, an elongated tool may be connected to the pin placement PSI 30by way of the socket 36, for its distal manipulation.

As shown concurrently in FIGS. 4 and 5, pins 40 are drilled into thescapula A. The pins 40 may be provided with sleeves 41 (a.k.a.,bushings) received in a planned fit (e.g., precise fit) that will ensurethat the pins 40 are axially centered in the slots 34, as the sleeves 41have throughbores centered with the slots 34. Moreover, the sleeves 41may comprise abutment ends 42 to control the depth of insertion of thepins 40 in the glenoid. Any appropriate methods are also considered tocontrol the depth of insertion of the pins 40, such as graduating thepins 40 with a scale, etc.

In operation, handle 43 is connected to the socket (FIGS. 3 and 4), andthe pin placement PSI 30 is installed onto the glenoid B with theanatomical interface 31 ensuring that the pin placement PSI 30 isproperly positioned on the scapula A, by laterally moving the pinplacement PSI 30 into planned position on the bone. The pins 40 withsleeves 41 thereon are inserted in the slots 34 of the pin placement PSIvia the lateral openings 35, and may hence be drilled into the glenoidB, or the sleeves/bushings 41 may be placed in the slots 34 prior tothreading the pins 40 therein. Once the pins 40 are suitably inserted inthe scapula A, the sleeves 41 may be withdrawn by sliding them off theend of the pins 40 shown in FIG. 5, thereby allowing the removal of thepin placement PSI 30 from the scapula A by a lateral movement. Thesurfaces of the hook-like portion of the anatomical interface 31 aregenerally transverse to a longitudinal direction of the drill guide 33.The presence of the lateral openings 35 allows a good contact surfacebetween the hook-like portion of the anatomical interface 31, withouthaving difficulties in the lateral withdrawal of the PSI 30 as the pins40 pass through the lateral openings 35.

According to the illustrated embodiment, one of the pins 40 is at acenter of the anticipated resurfaced glenoid cavity C, while the otherpin 40 is located adjacent to the superior glenoid rim in alignment withthe coracoid or at the base of the coracoid. Other positions are alsoconsidered. For illustrative purposes, a contemplated position of thepin placement PSI 30 is generally shown relative to the scapula A inFIG. 16.

Referring to FIG. 1, a step 14 of depth drilling and/or surface reamingon the glenoid B is performed using the pins 40 and an appropriate PSI.Referring concurrently to FIGS. 6 and 7, a reaming PSI is generallyshown at 60. The reaming PSI 60 has a first tube 61 with a pin slot 62that is dimensioned to be slid onto one of the pins 40, thereby forminga cylindrical joint therewith. An end of the first tube 61 defines anabutment 63 to abut against the scapula A. A spacing arm 64 extendslaterally from the first tube 61 and has at its free end a second tube65. The second tube 65 also comprises a shaft slot 66, which shaft slot66 is laterally accessible via a lateral opening 67, used to rotate thereaming PSI 60 such that the pin 40 enters the shaft slot 66. As thereaming PSI 60 is patient specific, the pin slots 62 and the shaft slot66 are spaced apart by a predetermined distance to match the spacingbetween the pins 40. Hence, as shown in FIG. 7, when the first tube 61is slid onto one of the pins 40, the other pin 40 may be oriented to bewithin the shaft slot 66 of the second tube 65.

It is pointed out that step 14 may comprise a verification of thelocation of the pins 40. As the reaming PSI 60 is fabricated to receivethe pins 40, the centrally-located pin 40 should be axially centered inthe second tube 65. Any off-centering may indicate improper positioningof the pin 40, and such indication may cause a review of step 13 toreposition the pins 40.

Referring to FIG. 8, a cannulated reamer 80 may therefore be installedonto the pin 40 that is within the shaft slot 66, so as to be coaxiallyguided by the pin 40 in translation. The reamer 80 has a reamer end 81that is selected to perform resurfacing of a planned diameter in theglenoid B. The reamer end 81 is located at the end of a shaft 82. Theshaft 82 is sized to be received in the shaft slot 66 of the reaming PSI60, to form the translational joint. Moreover, the reamer end 81 mayalso drill a bore of sufficient diameter to receive the peg 22 of theimplant 20 therein (FIG. 2), to a depth defined by abutment against thereaming PSI 60. The drilling of the peg bore may alternatively be doneseparately. Accordingly, the combination of the pin 40 in the cannulatedreamer 80 and the cooperation between the shaft 82 and the shaft slot 66ensures that the glenoid B is reamed specifically where desired to adesired depth. The shaft 82 enters the shaft slot 66 by being slid orsnapped into it. Still referring to FIG. 8, a stopper 83 may beinstalled on the end of the shaft 82. The stopper 83 cooperates with thereaming PSI 60 to limit the depth of penetration of the reamer 80 in theglenoid B, to ensure that the surface reaming and optional depthdrilling (if done separately for the peg 22 of FIG. 2) have a planneddepth.

It is observed that both pins 40 are used to support the reaming PSI 60and guide movement of the cannulated reamer 80. By using both pins 40,the structural integrity of the pin 40/PSI 60 assembly is increased overa single pin 40. However, it is considered to use any otherconfiguration, for instance using a single pin 40, with the cannulatedreamer 80, the reamed the glenoid B.

As shown in FIG. 9, once the glenoid B has been reamed to define theresurfaced glenoid cavity C with peg bore D, the depth drilling PSI 60may be removed along with the pins 40. Although not shown, it may bedesired to keep the pin 40 that is not in the resurfaced glenoid cavityC, as explained hereinafter. In the case in which the wedge graft B1 isused (FIG. 15), the wedge graft B1 is installed at the adequate positionon the glenoid B, adjacent to the resurfaced glenoid cavity C. The pin40 on the coracoid may be used to guide an operator in properlyorienting the wedge graft B1. The wedge graft B1 may be fused to theglenoid B, and the screws 23 will secured both the implant 20 and thewedge graft B1 to the glenoid B.

Referring to FIG. 1, a step 15 of impacting the implant 20 is performed,using one of the pins and PSI for properly orienting the implant 20.More specifically, the orientation of the implant 20 will have an impacton the positioning of the screws 23 (FIG. 2). Hence, in order toreplicate the virtual planning of step 11, the implant 20 must becorrectly oriented so as to have the throughbores 26 aligned with theplanned location of insertion of the screws 23.

Referring concurrently to FIGS. 10 and 11, an impacting guide PSI isgenerally shown at 100. The impacting guide PSI 100 comprises a tube 101with a pin slot 102. The pin slot 102 is sized so as to receive thereinthe remaining pin 40 and form therewith a cylindrical joint. An abutmentend (with any appropriate shape/geometry) 103 of the tube may have apatient-specific contact surface shaped to rest against a surroundingbone surface and hence prevent rotation of the PSI 100 when the tube 101abuts the bone. An arm 104 projects laterally from the tube 101. A guidebracket 105 is at a free end of the arm 104 and is used to guide themovement of an impactor tool 110. More specifically, the guide bracket105 has a lateral opening for receiving therein a shaft 111 of theimpactor tool 110 to form a sliding joint therewith.

The impactor tool 110 may be conventional, with a pair of pegs spacedapart to be received in the throughbores of the implant 20 (FIG. 2). Theguide bracket 105 is specifically oriented as a function of a locationof these pegs at the end of the shaft 111 of the impactor tool 110, tocontrol the positioning of the throughbores 26 of the implant 20, inaccordance with the virtual planning step 11 (FIG. 1).

Hence, with the assembly of FIG. 11, the implant 20 may be inserted intothe resurfaced glenoid cavity C. The matching shape of the implant 20and resurfaced glenoid cavity C may result in a self-centering of theimplant 20 during impacting (and therefore not necessitating thepatient-specific surface at the abutment end 103 to perform analignment). However, the PSI 100 and impactor tool 110 generally ensurethat the implant 20 is fully inserted in the resurfaced glenoid cavityC, with the throughbores 26 located where planned. At this point, thePSI 100 may be removed with the impactor tool 110 leaving the implant 20in the resurfaced glenoid cavity C.

According to step 16 of FIG. 1, anchor holes may be drilled in theglenoid as planned, for the subsequent insertion of the screws 23.Referring to FIGS. 12 and 13, a drill guide PSI 120 has a body 121 sizedto be received in a corresponding cavity in the implant body 25. A pairof drill guide bores 122 are defined in the body 121 of the drill guidePSI 120. The drill guides bores 122 are specifically located andoriented to have guiding cylinders 122A in axial extension of thethroughbores 26 in the implant 20 (FIG. 2). Moreover, the diameter ofthe guiding cylinders 122A is generally tapering to center a drill bit123 therein, to reduce any potential play between the drill bit 123 andthe drill guide bores 122. The material used for the body 121 of thedrill guide PSI 120 may also be selected so as not to be damaged by thedrill bit 123. As shown in FIG. 13, a stopper 124 may be provided on thedrill bit 123 to control the drilling depth to reach the planned depthfor the anchor holes. Alternative methods are considered as well, suchas graduating the drill bit 123 with a scale, to control the depth. Oncethe anchor holes have been drilled, the drill guide PSI 120 may beremoved. As shown in FIG. 12, the drill guide PSI 120 may also comprisea visual pointer 125. The visual pointer 125 may be patient-specificallyformed in the drill guide PSI 120 to point at the remaining pin. Thistherefore represents an additional verification step to ensure that theholes are drilled at the desired location.

According to step 17 of FIG. 1, screws 23 (or like fasteners) may securethe implant 20 to the scapula A, replicating the virtual planning ofFIG. 2. Conventional steps are then performed to finalize the shouldersurgery.

It is pointed out that the method 10 may include a step of creating thegraft B1 of FIG. 15. The step of method 10 may include providing a PSItool for the removal of bone material, for instance from the humerus, asthe humerus must be resurfaced. However, the graft B1 removed from thehumerus or other bone may simply have a cylindrical shape, and hence astandard cylindrical reamer of appropriate diameter may be used. As thegraft B1 is shown as having a wedge shape in FIG. 15, an appropriate PSItool may be created to machine the oblique plane of the graft B1.

While the methods and systems described above have been described andshown with reference to particular steps performed in a particularorder, these steps may be combined, subdivided or reordered to form anequivalent method without departing from the teachings of the presentdisclosure. Accordingly, the order and grouping of the steps is not alimitation of the present disclosure.

1. A system for installing an implant on a bone having at least a pairof pins placed in known patient specific positioning relative to thebone, the system comprising: a reaming instrument having at least afirst tube configured to be slid onto one of the pins to be slid alongthe pin, and a second tube spaced from the first tube to be aligned withthe other one of the pins; and a cannulated reamer having a reamer endconfigured to ream the bone, and a hollow shaft supporting the reamerend and configured to be driven, the hollow shaft concurrently receivedin the second tube of the reaming instrument and mounted onto the otherof the pins, for the reaming instrument to guide movement of thecannulated reamer when reaming the bone.
 2. The system according toclaim 1, wherein the second tube of the reaming instrument has a lateralshaft slot for receiving the hollow shaft of the cannulated reamer. 3.The system according to claim 1, wherein the second tube of the reaminginstrument forms an abutment at a given height from the bone, andwherein the hollow shaft of the cannulated reamer has a stopper (83),whereby the stopper (83) and abutment concurrently act to limit a depthof reaming.
 4. The system according to claim 1, wherein the first tubeand the second tube of the reaming instrument are parallel to oneanother.
 5. The system according to claim 1, further including the pins,with a first of the pins placed in a planned glenoid implant center, anda second of the pins located away from the glenoid.
 6. The systemaccording to claim 1, wherein the reamer end is sized as a function of aplanned glenoid implant size.
 7. The system claim 1, further comprisingan impacting guide having a guide tube configured to be slid onto one ofthe pins to be slid along the pin after removal of the reaminginstrument after reaming, and a guide bracket spaced from the guide tubeto be aligned with a reamed surface of the bone, the guide bracketconfigured to receive a shaft of an impactor tool.
 8. The systemaccording to claim 7, wherein the guide bracket has a lateral openingconfigured to receive the shaft of the impactor tool.
 9. The systemaccording to claim 7, wherein the guide tube has an abutment endconfigured to contact the bone to prevent rotation of the impactingguide relative to the bone and pin.
 10. The system according to claim 9,wherein the abutment end has at least one patient specific surface basedon an anatomical model of the patient.
 11. The system according to claim7, further comprising the impactor tool, the impactor tool having theshaft for guidingly engaging the guide bracket, and an end forsupporting an implant.
 12. The system according to claim 1, furthercomprising a pin placement instrument for placing the pins, the pinplacement instrument comprising an anatomical interface with a hook-likeportion being opened in a lateral direction of the instrument to receivea bone therein in a planned position, a drill guide connected to theanatomical interface and defining guide slots in a longitudinaldirection of the instrument, the guide slots each having a lateralopening over its full length in the drill guide to allow lateralwithdrawal of the instrument in said lateral direction with the pinplaced in the bone passing through the lateral opening, and a bushingremovably placed in each said guide slot via said longitudinal directionin a planned fit, the bushings defining a throughbore aligned with theguide slot and adapted to receive the pin extending in said longitudinaldirection when the bushing is in the guide slot for pin placement. 13.The system according to claim 12, wherein the anatomical interface witha hook-like portion has at least one patient specific surface based onan anatomical model of the patient.
 14. The system according to claim 1,wherein one of the pins is longitudinally aligned with a center of ananticipated resurfaced glenoid cavity, and another one of the pins islocated adjacent to the superior glenoid rim in alignment with thecoracoid or at a base of the coracoid.
 15. The system according to claim1, further including a glenoid implant.
 16. An system for installing animplant on a bone of a patient, the system comprising: an impactingguide having a guide tube configured to be slid onto a pin adapted to beplaced into the bone proximate a reamed surface of the bone, and a guidebracket spaced from the guide tube to be aligned with the reamed surfaceof the bone; and an impactor tool having a shaft for guidingly engagingthe guide bracket of the impacting guide, and an end for supporting theimplant.
 17. The system according to claim 16, wherein the guide brackethas a lateral opening configured to receive the shaft of the impactortool.
 18. The system according to claim 16, wherein the guide tube hasan abutment end configured to contact the bone to prevent rotation ofthe impacting guide relative to the bone and the pin when the impactingguide is in use.
 19. The system according to claim 16, wherein theimpacting guide includes an arm connecting the guide tube to the guidebracket.
 20. The system according to claim 16, further including thepin.